Beta radiation call a stream of positrons or electrons which arises at radioactive decay of atoms. Passing through any substance of a beta particle spend the energy, interacting with kernels and electrons of atoms of the irradiated material.
Instruction
1. Positrons are positively charged beta particles, and electrons — negatively charged. They are formed in a kernel at transformation of a proton into a neutron or a neutron in a proton. Beta beams differ from secondary and tertiary electrons which appear as a result of air ionization.
2. At an electronic beta decay the new kernel which number of protons are one unit more is formed. At positron disintegration the charge of a kernel increases by unit. In either case the mass number does not change.
3. At beta beams a continuous power range, it is caused by the fact that excess energy of a kernel is distributed differently between two let-out particles, for example, between a neutrino and a positron. For this reason for a neutrino the continuous range is also characteristic.
4. Beta beams — one of types of ionizing radiation, they lose the energy, passing through substance, cause ionization and excitement of atoms and molecules of the environment. Absorption of this energy can lead to secondary processes in the irradiated substance — a luminescence, radiochemical reactions or change of crystal structure.
5. A run of a beta particle call a way which it passes. As a rule, this size is expressed in grams on square centimeter. Beta radiation gets into body tissues on depth from 0.1 mm to 2 cm. For protection against it it is enough to have the screen from organic glass of the same thickness. At the same time the layer of any substance which area density exceeds 1 g / sq. cm almost completely absorbs beta particles with energy of 1 MeV.
6. The penetration of beta particles is estimated on their maximum run, it is much less, than at gamma radiation, but 10 times more than at alpha radiation. Under the influence of electric and magnetic water beta particles deviate from the rectilinear direction, at the same time their speed is close to the speed of light.
7. Beta radiation is used in medicine for superficial, intracavitary and interstitial radiation therapy. It is also applied in the experimental purposes and to radio isotope diagnostics — recognition of diseases by means of connections, marked radioactive isotopes.
8. The medical effect of beta therapy is based on biological effect of beta particles which are absorbed by pathologically changed fabrics. As sources of radiation various radioactive isotopes are used.